Laser treatments are nowadays widely used in cosmetics, dermatology and surgery. A wide selection of laser devices are available for these purposes, such as:
Neodymium Yttrium-Aluminium-Garnet Laser [Neodymium:YAG] (1064 nm)
    This laser provides a high penetration depth and produces a photothermolysis. By superposition of a potassium titanyl phosphate crystal the frequency can be doubled, thus halving the wave length to 532 nm. The emerging green light is well absorbed by structures containing melanine or oxyhemoglobin. Thus, this laser is used for the treatment of epidermic pigmented lesions.Ruby Laser (694 nm)    The red light of the ruby laser, which is very well absorbed by melanin and dark colored particles, is suitable for the treatment of Lentigo benigna (café au lait spot) for its short exposure time (25 to 40 ns) by which the thermic lesion of the surrounding tissues is minimized.Alexandrite Laser (755 nm)    This laser is suitable for the treatment of dark tattoos.CO2-Laser(10′600 nm)    The light of this laser is absorbed by the tissue fluid which results in coagulation and vaporization of the tissue. In its continuous wave mode this laser can be used as a light scalpel. However, in its pulsed mode this laser is well suitable for “Skin Resurfacing”. Thereby, the uppermost dermal layers (Stratum corneum and epidermis) can purposefully and extensively be removed. A total ablation of the face is often made for producing a visible rejuvenation. By a selective photothermolysis the removal of the skin happens faster than the generation of heat. Besides the removal of the epidermis, the residual heat provokes a firming of the connective tissue as well a new synthesis of collagen. The regrowing skin is free from wrinkles and scars.Erbium Yttrium Aluminium Granat Laser [Erbium:YAG] (2940 nm)    This pulsed laser has an indication spectrum which is similar to that of the CO2-laser. However, the thermic tissue effect is lower. Thus, the painfulness and the risk of scars formation is reduced. However, this advantage is partially neutralized by the fact that the operation method is bloody. By the use of this laser skin layers of a thickness of 5 to 15 μm can purposefully be removed. Thus, this laser is also particularly useful for cosmetic treatments.
The possibilities of laser treatment are very wide and are permanently improved. A synopsis is given in the publication Michael Drosner, Kosmetologika 2001, Supplement 1/2001, pages 8 to 10.
In chemical peelings the uppermost skin layer is removed as well, this time by aggressive chemicals. Thereafter, the regrowing skin is rejuvenated. This becomes apparent by a reduction of wrinkles and of the roughness of the skin. For such chemical peelings, substances such as phenol, trichloroacetic acid, α- and β-hydroxyacids (glycolic acid, lactic acid, salicylic acid) are used in various concentrations. After treatment of the skin with these substances in various concentrations for several days the skin is irritated and shows an increased transepidermal water loss.
All laser treatments and chemical treatments of the skin produce slight or severe wounds which are to be treated with cosmetic or pharmaceutical products to enable the skin to resume its normal function. Besides the cooling effect of an aftercare, there is a need for occlusive measure in order to reduce the transepidermal water loss and to protect the open skin against environmental influences, such as micro-organisms, dirt, viruses, or chemicals. Immediately after the laser treatment a protection by a foil or a vulnerary gel is often applied. However, creams or ointments are used for an extensive aftercare.
At present quite a number of products for the post-treatment of skin damaged by laser treatments and chemical peelings are on sale and used. Most of these products are based on a vaseline formulation, such as e.g. “Aquaphor®” of Beiersdorf AG, Germany, and “Catrix 10®” of Lescarden Inc., USA. These products are very simple, relatively reasonable in price, and they produce a good occlusion. A further advantage of these products is that they contain no or only very little water, and thus need not to be preserved.
However, an important disadvantage of these products is that they comprise a fatty component on the basis of mineral oils, and thus are not optimal for skin regeneration. Furthermore, these formulations are unsuitable for the incorporation of aqueous active components having wound healing properties, such as e.g. dexpanthenol. A further disadvantage is that they produce an unpleasant greasy skin-feeling.
A better skin-feeling and a more pleasant application can be reached by using creams. Therefore, such oil-in-water or water-in-oil formulations are used for post-laser treatments and after chemical peelings, such as e.g. “Post-Laser Treatment Kit®” of Skin Medica, USA, and “Nutritive Moisturizing Calendula Cream®” of TT Cosmetica Activa, Spain. Such emulsions allow a wider scope in using active components which promote wound healing and regeneration of the skin. However, very often such products contain compounds which provoke irritations and allergic manifestations, such as e.g. preservatives, perfumes, or plant extracts. However, a most important disadvantage of such formulations is the presence of water-in-oil and oil-in-water emulsifiers. These compounds negatively influence the skin regeneration. Moreover, they also emulsify the skin lipids, by which the formation of a barrier function is deteriorated.
As said above, laser treatments and chemical peeling produce very similar surface effects, inasmuch as they remove the uppermost dermal layers, i.e. Stratum corneum and epidermis. The skin then no longer comprises any corneocytes.
The publication WO 97/16166, corresponding to U.S. Pat. Nos. 5,738,543 and 5,851,543, describes methods for treatment of human skin by enhancing formation of lamellae between corneocytes within the skin by topical application of a bilayer component that is a mixture of a negatively charged phospholipid and a triglyceride. The compositions to be applied also comprise mineral oils. Such treatments are completely different from the post-treatment of skin damaged by laser treatments or chemical peelings, because—as said above—the damaged skin does no longer comprise any corneocytes.
The publication WO 98/55082 describes a dermatological healing kit which comprises a pigment stabilizer and anti-inflammatory emollient, and which is said to be useful for post-treating skin after laser treatments. The purpose of using this kit is to avoid darkening of the laser treated skin and to relieve skin inflammations. However, this kit is unsuitable for rebuilding the uppermost dermal layers, i.e. Stratum corneum and epidermis, of skin damaged by laser treatment or chemical peelings.
U.S. Pat. No. 4,454,159 describes a dermatological composition comprising a special combination of lipids/lipoids which is said to soothe and condition irritated, pruritic and dry skin. However, this composition too is unsuitable for rebuilding the uppermost dermal layers, i.e. Stratum corneum and epidermis, of skin damaged by laser treatment or chemical peelings.
Finally, the publication FR 2,794,366 describes a dermatological composition comprising a ceramide, cholesterol, fatty acids, a triglyceride, lecithin, and phytosphingosine. This composition is said to be useful in treating skin damaged by cuts, burns, inflammations or acne. However once again, this composition is unsuitable for rebuilding the uppermost dermal layers, i.e. Stratum corneum and epidermis, of skin damaged by laser treatment or chemical peelings.